ST segment depression: the possible role of global repolarization dynamics.

Area of Science:

• Cardiovascular Physiology
• Biomedical Engineering
• Computational Modeling

Background:

• Clinical data indicates early ST segment patterns in myocardial ischemia show a minimum near lead V5 and negative potentials.
• Late ST segment potentials have shown potential for localizing ischemic heart regions.

Purpose of the Study:

• To model the heart/torso system to understand the link between transmembrane potentials and body surface potential patterns during ST segments in ischemia.
• To investigate early and late ST segment patterns in ischemic patients using a computer model.

Main Methods:

• Developed a computer model of the heart/torso system.
• Adjusted transmembrane potentials to replicate observed clinical body surface potentials.

Main Results:

• Early ST segment patterns were reproduced by simulating normal activation/repolarization sequences with specific epicardial and endocardial transmembrane potential gradients.
• Late ST segment potentials, capable of localizing ischemia, were generated by modifying epicardial and endocardial transmembrane potential gradients.

Conclusions:

• Global transmembrane potential gradients during activation/repolarization may explain the non-localizing nature of early ST depression.
• Altered epicardial and endocardial transmembrane potential gradients, particularly an increased endocardial gradient, may account for the localizing ability of late ST depression.